Prickly Richard's Cactus Page.

named cacti list

taxonomy of the cactus

The information in the next four sections is sourced mostly from the book, "Cacti of the desert South-west" by Meg Quinn and published by Rio Nuevo Publishers in the United States and from the Cactus page in the Wikipedia on-line encyclopedia.

evolution of cacti

250 million years ago the Americas were joined to the continents of Africa and Europe. Around 200 million years ago the giant super continent of Pangea was starting to break up due to continental drift, resulting in the separation of the Americas from Europe and Africa. Cacti are a native to the Americas and are believed to have evolved in the last 30 to 40 million years when the Americas were already separated by a considerable distance from Europe and Africa. They have in more recent times been introduced and naturalised in various parts of the world where similar climatic conditions prevail. They grow mostly in desert conditions but there are also some that grow in rainforests as epiphytes on tree branches One species, 'Rhipsalis baccifera' which occurs in parts of Africa and Asia as well as the Americas is thought to have been introduced relatively recently after being dispersed by migratory birds.

range

Their range on the american continent is as far north as Canada and as far south as Argentina. In the south-west United States the Mojave desert (about twenty-five species at elevations between sea level and 4,000 feet), the Sonoran desert (about one hundred species at elevations between below sea level and 3,500 feet) and the Chihuahua desert (more than 300 species at elevations between 1,000 feet and 6,000 feet) are of special importance. The Sonoran desert and the Chihuahua desert in particular also cover large areas in Mexico.

what is a cactus?

Many succulent plants in both the Old and New World bear a superficial resemblance to cacti due to parallel evolution without being closely related to the Cactaceae. The Cactaceae are one of several plant families containing succulents. Succulents have an enhanced capacity for storing water in leaves, stems or roots. This has evolved in response to their dry environments. Cacti come in a great variety of shapes and forms but have clearly defined chacteristics of their own. The stem surfaces may be smooth but are more likely to have "tubercles" which are in fact enlarged leaf bases. They may be nipple-like, triangular or in the form of vertical ribs. There are some tropical cacti that have large leaves but most species have none. The cholla and the prickly pear species produce tiny short-lived leaves in Spring. In order for a plant to be a cactus it must have areoles. Areoles are unique to cacti and are specialized structures consisting of small pads or cushions from which spines and flowers emerge in most species. The spines of cacti are considered to be modified leaves. They may be all the same or the outer radial spines may be different from the inner central spines. Spines protect the plants from being eaten, help reduce water loss by slowing air movement and provide shade. Flowers are in a range of beautiful colours other than blue and may be pollinated by bees, birds, bats, moths, butterflies and other insects. Flower colour, shape, fragrance and time of opening are all influences on plant-pollinator relationships. Fruits containing seeds develop and are eaten by birds and other creatures and dispersed.

name that cactus!

One of the difficult things about cacti is being able to accurately name them given the large range of genera and species. The estimate of the number of genera of cacti vary according to the source from between 24 and 220 genera, with around 90 genera being the most widely accepted count, and with anywhere from 1,500 to 1,800 species. A single genus may contain species that differ markedly in appearance. A particular species may also have several different obsolete synonyms in different genera. At the end of the 80's the IOS (International organization for succulent plant studies) worked on a reorganization of the genera of the Cactus family. This resulted in many cacti being reallocated to different genera. Some genera became obsolete. This partly helps explain why I have not been able to name some of the cacti. If you think you can help with identification please feel free to contact me by email. See address at end of page.

how to grow cacti

Cacti need to have well drained soil and should never be allowed to get waterlogged. Cacti are famously drought tolerant but in order for them to grow they should be watered in the growing season, preferably in the evening. Water should not get onto the surface of the plant in hot, sunny weather as this could cause scorching. I wait till the soil has dried out before each watering. Cacti also need good ventilation especially in warm weather and like plenty of sunlight. Tiny seedlings however need shading from strong sunlight, as they will otherwise turn brown and die. They are also vulnerable to damping off. Forest cacti appreciate more shade than desert cacti. They can be occasionally fed during the growing months, (April to October).

For potting, on I bought a bag of proper bona fide cactus compost for the first time in 2004 . Before this I would mix various combinations of peat, vermiculite, sharp sand and soil depending on whatever I had available at the time and use this whenever I needed to transfer the cactus to a larger pot. As cacti usually have sharp spines (or in the case of those such as "Opuntias", irritating hairs called glochids), it is advisable to wear gardening gloves when doing this. Gently squeeze the sides of the pot to ease out the plant if necessary.

how not to grow cacti

I know that cacti are traditionally supposed to be easy to look after and in a lot of ways they are but in the winter of 2003/4 I managed to kill off quite a lot of cacti. Due to lack of space and so as to save non hardy plants from the winter cold of the outdoor greenhouse I put them in the kitchen on top of wall units and what with the cooking fumes and lack of ventilation they were so stressed that quite a few died. They should of course have been put in an unheated room. They or at least some of them were already suffering from mealy bug infestation that of course made them even more vulnerable.

The 'cleistocactus' was not left in the kitchen but in a heated room over the winter of 2003/4. It rotted off at the top as a result and had to be cut back in the spring of 2004.

propagation

The first time I sowed a packet of cactus seeds must have been back in 1985. Of the dozen or so that germinated I only have one left and that one has now reached a reasonable size though has yet to flower and is still to be named. Several were left behind in the glasshouse where I used to work as a gardener at the Medical Research Council in Mill Hill in North London. Since then I have had limited success growing from seed. Young cactus seedlings are prone to damping off even when they appear to be doing well. The seedlings also grow very slowly in the first few years of life. However the stenocereus thurberi', (Organ Pipe Cacti) that I still have were all grown from seed in about 1995 and have grown well in 2004 and 2005 and continue to do so in 2006.

I have also successfully taken cuttings of 'opuntia', 'mammillaria', 'rebutia'and Winter and Easter Cactus. The cutting is first removed with a clean sharp knife and left to dry out for a period of between two days and two weeks depending on the size of the cutting. Rooting powder can be applied and the cutting is then placed with the cut end just below the surface of the compost. After a day or so it may be watered sparingly.

mealy bug infestation

In 2003 Mealy bugs attacked many of the cacti for the first time. The mealy bug infections show as white cotton wool like deposits which is a protective waxy layer, under which are the mealy bugs themselves. They suck the sap of the plant, weaken it and can introduce infections and rotting. After using a chemical pesticide which killed a couple of cacti faster than the mealy bugs had done, I settled on white spirit that can be applied with a cotton bud. If a cactus is hardy enough to be left outside in a green house over winter it is best to do so as mealy bugs favour warm conditions dislike the cold.

beware the digger bee!

For the past two or three years some kind of bee-like insect has been digging holes beneath cacti. I thought it was quite cute to have it flying in with cut of pieces of leaf to furnish its nest every few minutes during the summer but unfortunately it seems that wherever the digger makes its hole the cactus later dies. The 'mammillaria' pictured with pink flowers and a 'trichocereus' which on only one occasion produced a beautifully scented nocturnal white flower have both died, probably from root damage, after acting as hosts. I saw the bee buzzing around in and out of a pot containing a "stenocereus thurberi" cactus. This time after briefly wrestling with my conscience which I am glad to say put up little resistance. I put an end to the digger bee by vigorously poking a stick into the hole that it had dug when it was in the hole.

Warning!
This Poem might upset readers of a sensitive disposition or on the other hand it might not.

I killed the digger bee
I killed the digger bee
T' was not revenge
That's not my way
But the digger bee had come to stay
She buried her leaves beneath the earth
So what is the life of a cactus worth?
Cacti shrivelled and died
So I broke down and cried
I poured in some water
To enable the slaughter
But the bee got away
And the very next day
I saw her again
I felt anger and pain
She flew into her nest
Then I did the rest
I picked up a small stick
And I poked and I poked
And inside the nest
The bee choked then she croaked
And now she is dead
Nothing more to be said.

where I keep cacti in the summer and winter

In springtime I return cacti from indoors to an unheated greenhouse. I live in North London and if a cactus is hardy enough to leave in the unheated greenhouse over winter then all well and good. The difficulty is in knowing which are hardy enough and which aren't as I have limited space indoors. Generally I think that the smoother cacti with fewer spines are less hardy and the more spiny and furrier are hardier. It is partly trial and error, though in order not to kill off too many I err on the side of caution. They need to be kept in an unheated room in winter otherwise they are prone to rot even though kept dry.

cactus photos

All the pictures of cacti and the cacti themselves on this page are my own, or in the case of those that have died were my own. The photos below were all taken from the Spring of 2004 onwards using a Minolta Dimage E323 digital camera. Message tags are viewable in Internet Explorer. Please fell free to email me especially if you can positively identify any of the cacti at chilepine (at) blueyonder (dot) co (dot) uk.

Stenocereus genus (I think) previously lemairocereus. Bought on a cold post-Xmas morning in Folkestone, Kent in 2001/2 along with the vigorous cleistocactus; this cactus grows slowly.

Cactus Obituaries and Photos

I'm so lucky (2006 additions)

In March 2006 I was given loads of cacti and quite a few succulents, numbering about fifty in total. They belonged to a gentleman who had to go into a nursing home. They are really nice ones and I need to find out about them and look after them well. Quite a number of them have already flowered beautifully. I have taken photos of those that have flowered but what about their names! Trawling systematically through pictorial databases is too much like hard work so I shall name them when and if I serendipitously stumble across them, figuratively speaking.

last updated: 25/04/2008

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